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snow line

 
Dictionary: snow line
 

n.
  1. The lower altitudinal boundary of a snow-covered area, especially of one that is perennially covered, such as the snowcap of a mountain.
  2. The fluctuating latitudinal boundaries around the polar regions marking the extent of snow cover.

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A term generally used to refer to the elevation of the lower edge of a snow field. In mountainous areas, it is not truly a line but rather an irregular, commonly patchy border zone, the position of which in any one sector has been determined by the amount of snowfall and ablation. These factors may vary considerably from one part to another. On glacier surfaces the snow line is sometimes referred to as the glacier snow line or névé line (the outer limit of retained winter snow cover on a glacier).

Year-to-year variation in the position of the orographical snow line is great. The mean position over many decades, however, is important as a factor in the development of nivation hollows and protalus ramparts in deglaciated cirque beds. See also Glaciology; Snowfield and névé.


 
Columbia Encyclopedia: snow line
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snow line, altitude above which or latitude beyond which snow does not melt in summer (usually called the permanent snow line), or, in winter, the line to which snow extends at a given point in time. Factors affecting the location of the snow line are the quantity of snowfall, the steepness of the slope on which snow rests, the exposure of an area to the sun and prevailing winds, the type and velocity of the winds, and the presence or absence of large bodies of water. The level of the snow line is much lower in winter than in summer. It is also affected by distance from the equator, along which it is found at an altitude of c.3 mi (5 km); in polar regions it is at sea level.


 
WordNet: snow line
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Note: click on a word meaning below to see its connections and related words.

The noun has one meaning:

Meaning #1: the line on a mountain above which there is perpetual snow and ice


 
Wikipedia: Snow line
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Cotopaxi, Ecuador (5,897 m), seen from 3,700 m, with the snow line at approximately 5,000 m
Snow line in Alps

The climatic snow line is the point above which snow and ice cover the ground throughout the year. The actual snow line may seasonally be significantly lower.

The interplay of altitude and latitude affect the precise placement of the snow line at a particular location. At or near the equator, it is typically situated at approximately 4,500 meters (or about 15,000 feet) above sea level. As one moves towards the Tropic of Cancer and Tropic of Capricorn, the parameter at first increases: in the Himalayas the permanent snow line can be as high as 5,700 metres (18,700 feet). Beyond the Tropics the snow line becomes progressively lower as the latitude increases, to just below 3,000 metres in the Alps and falling all the way to sea level itself at the ice caps near the poles.

In addition, the relative location to the nearest coastline can influence the altitude of the snow line. Areas near a coast might have a lower snow line than areas of the same altitude and latitude situated in a landmass interior due to more winter snowfall and because the average summer temperature of the surrounding lowlands would be warmer away from the sea. A higher altitude is therefore necessary to lower the temperature further against the surroundings and keep the snow from melting in the summer.

Levels of the climatic snow line:

Svalbard 78°N 0300–0600 m
Scandinavia at the polar circle 67°N 1000–1500 m
Iceland 65°N 0700–1100 m
southern Scandinavia 62°N 1200–2200 m
Alps (northern slopes) 48°N 2500–2800 m
Central Alps 47°N 2900–3200 m
Alps (southern slopes) 46°N 2700–2800 m
Pyrenees 43°N 2600–2900 m
Caucasus 43°N 2700–3800 m
Karakorum 36°N 5400–5800 m
Transhimalaya 32°N 6300–6500 m
Himalaya 30°N 4800–6000 m
Kenya 4600–4700 m
New Guinea 2°S 4600–4700 m
Andes in Ecuador 2°S 4800–5000 m
Kilimanjaro 3°S 5500–5600 m
Andes in Chile 27°S 5800–6500 m
New Zealand 43°S 1600–2700 m
Tierra del Fuego 54°S 0800–1300 m
Antarctica 70°S 0000–0400 m

References

  • Charlesworth J.K. (1957). The quaternary era. With special reference to its glaciation, vol. I. London, Edward Arnold (publishers) Ltd, 700 pp.
  • Flint, R. F. (1957). Glacial and Pleistocene geology. John Wiley & Sons, Inc., New York, xiii+553+555 pp.
  • Kalesnik, S.V. (1939). Obshchaya glyatsiologiya [General glaciology]. Uchpedgiz, Leningrad, 328 pp. (in Russian)
  • Tronov, M.V. (1956). Voprosy svyazi mezhdu klimatom i oledeneniem [The problems of the connection between climate and glaciation]. Izdatel'stvo Tomskogo Universiteta, Tomsk, 202 pp. (in Russian)
  • Wilhelm, F. (1975). Schnee- und Gletscherkunde [Snow- and glaciers study], De Gruyter, Berlin, 414 pp. (in German)

See also


 
 

 

Copyrights:

Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2007. Published by Houghton Mifflin Company. All rights reserved.  Read more
Sci-Tech Encyclopedia. McGraw-Hill Encyclopedia of Science and Technology. Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved.  Read more
Columbia Encyclopedia. The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2003, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/  Read more
WordNet. WordNet 1.7.1 Copyright © 2001 by Princeton University. All rights reserved.  Read more
Wikipedia. This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Snow line" Read more

 

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